Mechanical, Vibration Damping and Acoustics characteristics of Hybrid Aloe vera /Jute/polyester composites

© 2024 The Author(s). Published by Elsevier B.V. This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial 4.0 International License (CC BY-NC), https://creativecommons.org/licenses/by-nc/4.0/The development of biodegradable hybrid fibre composites is gaining pace in the automotive and construction industries due to their lightweight structural applications, which offer considerable benefits for the environment. In this present investigation, hybrid bio composites were fabricated using a compression molding machine with plain woven jute and aloe vera mats along with polyester resin as the matrix. Six types of hybrid biocomposite laminates were prepared by varying the stacking arrangement of jute and aloe-vera mats to analyse the impact of stacking arrangements on vibration damping and acoustic behaviour of these hybrid bio composites. From the results, it is concluded that the maximum value of natural frequency is obtained from the JJAJ type of composite. i.e., 157, 326, and 370 Hz for Modes I, II, and III respectively, due to good interlacing of fibres in the weft and warp directions. J/J/A/J (AJ3) hybrid bio composite has highest sound absorption coefficient of 0.47 at 3000 Hz, and a better transmission loss i.e 19.84 dB, according to the results of the acoustic research. The comparison of experimental and theoretical analysis was carried out, and found that experimental and theoretical values are closely related to each other.Peer reviewe

Feasibility of elastomeric composites as alternative materials for marine applications: A compendious review on their properties and opportunities

© IMechE 2022. This is the accepted manuscript version of an article which has been published in final form at https://doi.org/10.1177/14750902221095321The term elastomer is a curtailment of two words, which are elastic and polymers. Accordingly, elastomers are polymer materials with elasticity. The significant challenges hindering the development of materials for naval applications, similar to other engineering sectors, include achieving a competitive light elastomeric structure. Marine structures are susceptible to various damage responses due to various loads throughout their service life. Being flexible, elastomer has a low modulus of elasticity, exhibits higher values of failure strain and yield strength. In these regards, elastomers are attractive materials for applications that require elasticity because they offer substantial advantages compared to traditional materials. However, the low fire resistance of these elastomeric materials jeopardizes their use in some critical applications. As a result, elastomeric blends and composites containing flame retardant (FR) additives are commonly used. On the other hand, elastomers possess (i) high strength-to-weight ratio, (ii) excellent impact properties, (iii) low infrared, magnetic, and radar signatures, (iv) excellent durability, and (v) high resilience to extreme loads. Hence, the scope of this study focuses on review and awareness regarding the feasibility of marine applications of elastomers/ elastomeric composites, their current scientific and technological drawbacks, and future outlooks or prospects to support several applications in the marine industry.Peer reviewe

Identification of a Novel Gene Product That Promotes Survival of Mycobacterium smegmatis in Macrophages

BACKGROUND: Bacteria of the suborder Corynebacterineae include significant human pathogens such as Mycobacterium tuberculosis and M. leprae. Drug resistance in mycobacteria is increasingly common making identification of new antimicrobials a priority. Mycobacteria replicate intracellularly, most commonly within the phagosomes of macrophages, and bacterial proteins essential for intracellular survival and persistence are particularly attractive targets for intervention with new generations of anti-mycobacterial drugs. METHODOLOGY/PRINCIPAL FINDINGS: We have identified a novel gene that, when inactivated, leads to accelerated death of M. smegmatis within a macrophage cell line in the first eight hours following infection. Complementation of the mutant with an intact copy of the gene restored survival to near wild type levels. Gene disruption did not affect growth compared to wild type M. smegmatis in axenic culture or in the presence of low pH or reactive oxygen intermediates, suggesting the growth defect is not related to increased susceptibility to these stresses. The disrupted gene, MSMEG_5817, is conserved in all mycobacteria for which genome sequence information is available, and designated Rv0807 in M. tuberculosis. Although homology searches suggest that MSMEG_5817 is similar to the serine:pyruvate aminotransferase of Brevibacterium linens suggesting a possible role in glyoxylate metabolism, enzymatic assays comparing activity in wild type and mutant strains demonstrated no differences in the capacity to metabolize glyoxylate. CONCLUSIONS/SIGNIFICANCE: MSMEG_5817 is a previously uncharacterized gene that facilitates intracellular survival of mycobacteria. Interference with the function of MSMEG_5817 may provide a novel therapeutic approach for control of mycobacterial pathogens by assisting the host immune system in clearance of persistent intracellular bacteria

Performance evaluation of metal-coated fiber Bragg grating sensors for sensing cryogenic temperature

A metal recoated fiber Bragg grating sensor has been designed, fabricated and tested to study its temperature response at cryogenic temperature around 15 K. Metals like aluminium (Al), copper (Cu), lead (Pb) and indium (In) are considered for recoating the FBG sensors. Indium recoated FBG (IRCFBG) sensors showed a higher sensitivity at around 15 K compared to Al, Cu and Pb coated FBG sensors. In addition, the IRCFBG sensor was tested for its repeatability, stability and performance in the high magnetic field (8 T). The experimental results of the IRCFBG sensor test revealed a satisfactory performance. They will be reported in this paper. (C) 200

Plasma paraoxonase1 activity in rats treated with monocrotophos: a study of the effect of duration of exposure

We have earlier demonstrated the potential of monocrotophos (MCP), a highly toxic organophosphorus insecticide (OPI), to elicit insulin resistance in rats after chronic exposure. Given the understanding of role of paraoxonase1 (PON1) in OPI toxicity and diabetes pathology, this study was envisaged to understand the effect of duration of exposure to MCP on plasma PON1 activity in rats. Rats were administered MCP per os at 1/20 and 1/10th LD50 as daily doses for 180 days. Interim blood samples were collected at 15, 30, 45, 90 and 180 d for analysis of plasma parameters. Exposure to MCP for 45 resulted in persistent trend of hyperinsulinemia, while significant increase in fasting glucose levels was observed after 180 days. MCP caused suppression of plasma cholinesterase activity though the study period, albeit extent of inhibition was more severe during the early phase of the study. Exposure to MCP for 180 d resulted in hypertriglyceridemia and marginal decrease in HDL-C levels. MCP failed to modulate PON1 activity in plasma during the early phase of the study (up to 45 d). However, prolonged exposure resulted in significant increase in the plasma PON1 activity. This suggests that manifestation of insulin resistance in rats subjected to chronic exposure to MCP is associated with increase in PON1 activity. Our work provides rationale for studying whether the increase in PON1 activity observed in the present study serves to counter the deleterious effect of long term exposure to organophosphorus insecticides on metabolic homeostasis

Thermal and structural characterization of acrylonitrile butadiene styrene (ABS) copolymer blended with polytetrafluoroethylene (PTFE) particulate composite

© 2019 IOP Publishing Ltd.Anovel thermally sustainable polymer composite was fabricated with Acrylonitrile Butadiene Styrene (ABS) as the matrix and Polytetrafluroethylene (PTFE) particle as the filler, using injection molding process with 10 and 20 wt% PTFE filler. The composites were characterized by Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD) and Thermogravimetric analysis (TGA). The composites were also tested for their visco-elastic properties using Dynamic mechanical analyzer (DMA). The ABS/PTFE composites exhibited high thermal stability and better visco-elastic properties than the ABS matrix. Consequently, this hybrid blended polymer can be a suitable alternative material for tribological applications in both automobile and aerospace industries, among others.Peer reviewe